Probably no help here, but jumping from Sierra (with a Pascal-architecture Nvidia 1060 graphics card) to Monterey with an AMD RX6600, and going through Catalina with the internal graphics first, is something that would scare me. Just a few things to remember:
1. The last Mac OS to allow use of Pascal-architecture graphics is High Sierra 10.13.6. Obviously you already have that covered.
2. The last Mac OS to run both 32-bit and 64-bit applications is Mojave. Catalina and all later versions require all apps to be 100% 64-bit.
3. If you use Carbon Copy Cloner, it cannot copy both all data and all system files beyond Mojave; Apple's APFS file system (introduced in High Sierra), plus the Mac OS separating the System as read-only, makes copying stuff more complicated.
Sorry to sound so negative and wish I could help, but I don't have a 200-series motherboard, and trs96 is the best support you could get anywhere anyway. For whatever it's worth, IMHO OpenCore blows away Clover. (I am running OpenCore version 0.8.3 on Mini-ITX-1,3, and 4.)